More details:Fundamental premise: Universal Solvent (referred to as substance W) exerts extremely strong Van Der Waals interactions with just about anything, on the order of hydrogen bonding in strengthAssumptions:- W is chemically inert, it cannot carry any formal charge under any circumstances- W has poorer interactions with itself and is only liquid at rtp. Freezes a little under 0, boils at very high temperatures (think mineral oil)

Obviously, this breaks physics in a lot of ways but if you think of it as a really big single atom with the above properties, what sort of chemical purposes could you use it for?

Observable Properties:The first thing that comes to mind is that it is extremely corrosive in pure form (since it dissolves anything) and will behave similar to a soap in that addition of W will allow most liquids to mix.

I'm also thinking that W might dissolve small atoms (metals and ionic salts) faster than longer chains, and polymers might well be able to resist it for a long time. The only things that are completely immune to dissolution would be covalent single-crystals like diamond. In "looser" crystals with gaps, W might percolate through the gaps quite well too.

On the other hand, while W will eventually saturate given enough solute (depending on how the atomic packing goes, W might be able to absorb ludicruous quantities of solution), multiple solutes would compete on how well they stick to W. Gases might be easily displaced even if they are small as they have high entropy while longer chain polymers might refuse to crystallize out of solution.

A universal solvent that is chemically inert and can dissolve high quantities of anything might make for a good reaction medium. You could mix solids and liquids inside W much better than trying to grind out a lot of surface area on the solids. Perhaps some reactions might even change activation energy requirements, iron oxide reduction to iron with carbon monoxide might not require as much heat?

W might also be useful in chromatography as a mobile phase, although it might also destroy stationary phases by dissolving them too.

Well, you did say that covalent single crystals are the only known category of materials totally immune to dissolution, so "growing" crystal containers out of such material would work--e.g. a vapor-deposited coating of synthetic diamond on your container.